Enhancement of the superconducting transition temperature from the competition between electron-electron correlations and electron-phonon interactions

摘要

We uncover that the competition between electron-electron correlations andelectron-phonon interactions gives rise to unexpectedly huge enhancement of thesuperconducting transition temperature, several hundreds percent larger ($\geq$200 K) than that of the case when only one of the two is taken into account($\sim$ 30 K). Our renormalization group analysis claims that this mechanismfor the enhancement of the critical temperature is not limited onsuperconductivity but applied to various Fermi surface instabilities, proposingan underlying universal structure, which turns out to be essentially identicalto that of a recent study [Phys. Rev. Lett. {\bf 108}, 046601 (2012)] on theenhancement of the Kondo temperature in the presence of Rashba spin-orbitinteractions. We also discuss the stability of superconductivity againstnonmagnetic randomness.